Next, we examined LOH rates at MET15 in the SIR2OE strain to determine if increased Sir2 levels suppressed the age-associated change in LOH rates. Although MET15 LOH rates in young SIR2OE cells were significantly lower than the wild type strain (p<0.0001, Fisher's exact test based on contingency tables), we observed no difference in the timing or magnitude of the age-associated increase in MET15 LOH rates in SIR2OE cells compared to wild type (Figure 6B). This result offers further support that Sir2 protein levels are not the determining factor regulating rDNA recombination in aging cells.
